TWI745765B - Top electrode interconnect structures - Google Patents

Abstract

The present disclosure relates to semiconductor structures and, more particularly, to top electrode interconnect structures and methods of manufacture. The structure includes: a lower metallization feature; an upper metallization feature; a bottom electrode in direct contact with the lower metallization feature; one or more switching materials over the bottom electrode; a top electrode over the one or more switching materials; and a self-aligned via interconnection in contact with the top electrode and the upper metallization feature.

Description

Top electrode interconnect structure

The present invention relates to semiconductor structures, and in particular, to memory and manufacturing methods for interconnect structures embedded in integrated circuits (ICs).

Current methods of forming interconnections for top electrodes in embedded memory devices such as RRAM (Resistive RAM), PRAM (Phase Change RAM), MRAM (Magnetic RAM), FRAM (Ferroelectric RAM), etc. face many challenges. These memory devices include bottom metallization and top metallization, where there are top electrodes, switching materials, and bottom electrodes between these metal layers.

For example, there are challenges when forming the top electrode interconnection to expose the top electrode during the damascene line etching process. In this subtraction method, there is a narrow process window for the etching subtraction process. If the etching is too shallow, the connection has high resistance. If the etching is too deep, there is a risk of shorting to the switching layer. In order to solve these problems, the top electrode is usually made thicker, and if the top electrode material is too thick to be optically transparent, an additional covering mask is needed in turn.

If a via patterning process (rather than a wire) is used, challenges are also encountered during the top electrode interconnect manufacturing process. In this type of process, the vias may fall on the top electrode before the non-memory vias fall on the underlying metal layer. In this case, the loss of the top electrode during the etching process is high. Therefore, a thicker top electrode is used, which causes the above-mentioned problems. Since the height of the memory bit must be much smaller than the height of a single via, this type of The top electrode interconnect is also limited by scaling.

In one aspect of the present invention, a structure includes: a lower metallization feature; an upper metallization feature; a bottom electrode directly in contact with the lower metallization feature; one or more switching materials above the bottom electrode; A top electrode above the one or more switching materials; and a self-aligned via interconnection in contact with the top electrode and the upper metallization feature.

In one aspect of the present invention, a structure includes: a memory device including: a first metallization layer; a second metallization layer; and a vertical pillar connecting the first metallization layer to the A second metallization layer, the vertical post includes a self-aligned via interconnection contacting a top electrode of the vertical post and the second metallization layer; and a peripheral device or logic device, which includes the lower metallization The feature and the upper metallization feature, the lower metallization feature and the upper metallization feature are connected together by an interconnection structure without the self-aligned via interconnection and the vertical pillar.

In one aspect of the present invention, a method includes: forming a vertical column including a bottom electrode, one or more switching materials, a top electrode, and a mask material on the top electrode; An interlayer dielectric material is formed on the pillar; the interlayer dielectric material is opened to expose the mask material; the mask material on the top electrode is selectively removed to form a self-aligned via; A conductive material is deposited in the self-aligned via interconnection to form an interconnection, which is in contact with the top electrode; and a metallization layer is formed on the conductive material.

10: structure

10a: structure

10b: structure

10c: structure

12: Conductive wiring structure

12a: Conductive wiring structure

12b: Conductive wiring structure

14: Insulator material

16: Etch stop layer or diffusion barrier layer

18: bottom electrode material

20: Switch material

22: Top electrode material

24: Hard mask material

24a: Clearance wall material

24b: Lining material

26: vertical column

28: Dielectric materials

29: Interconnect

30: Self-aligned through hole

32: conductive material

Mx+1: groove

Vx: Through hole

Using non-limiting examples of exemplary embodiments of the present invention, the present invention will be described from the following detailed description with reference to the many drawings mentioned.

Figure 1 shows the top electrode, switching material, and bottom electrode and other features and corresponding manufacturing procedures according to various aspects of the present invention.

Figure 2 shows the post-damascene lithography and etching patterning process according to various aspects of the present invention to manufacture trench and via structures.

Figure 3 shows the self-aligned vias and other features aligned with a top electrode according to various aspects of the present invention and the corresponding manufacturing process.

FIG. 4 shows the post-metallization structure in the self-aligned through hole and the corresponding manufacturing process according to various aspects of the present invention.

5 and 6 show an alternative structure of defining a self-aligned through hole with spacer material according to another aspect of the present invention and the corresponding manufacturing process.

FIGS. 7 and 8 show an alternative structure of a defined self-aligned through hole having a liner material and a corresponding manufacturing procedure according to another aspect of the present invention.

Fig. 9 shows an alternative structure of a self-aligned through hole having a spacer material and a liner material according to another aspect of the present invention and the corresponding manufacturing process.

The present invention relates to semiconductor structures and particularly to top electrode interconnect structures and manufacturing methods. More specifically, the present invention provides a solid interconnect structure using metal wires to connect the top electrode of a memory device embedded in a metal layer and a manufacturing method. The top electrode interconnect structure can be implemented in memory devices, such as RRAM, PRAM, and MRAM, which are examples and not limited embodiments.

Advantageously, the present invention provides a means to reduce the thickness of the top electrode material, which has a lower top electrode resistance for interconnection to the upper wiring layer. In addition, the present invention provides a wider etching process window for the connection between the upper metal and the top electrode, and the cost is lower than the double-via patterning process. The process described herein also provides self-formed vias for the top electrode interconnect structure. In addition, there are few defects, such as non-volatile hard polymers used for through-hole patterning. In addition, implementing the structures and methods disclosed herein provides the freedom to remove hard masks (for example, TiN), which are used for dual damascene patterning to protect during wet etching or cleaning processes. Protect the top electrode metal.

In a specific embodiment, the top electrode is part of the interconnect structure between the lower and upper metal structures. For example, the interconnect structure includes upper metal interconnecting to the columnar features of the top electrode using a self-forming via patterning process. The interconnection structure to the top electrode can be formed without a through hole mask, thereby saving considerable cost. In another specific embodiment, the top electrode self-formed via is started and produced by the sacrificial hard mask material on the top of the top electrode, which has been used in the top electrode lithography and etching patterning process. In a specific embodiment, the hard mask material can be left after the top electrode/switch material/bottom electrode is formed, and then the dry or wet etching process disclosed during the patterning process of the interconnect structure to the upper metal layer The hard mask material is selectively removed (for example, after the deposition and planarization process of the interlayer dielectric material). As an example, self-forming vias include various types of features with dielectric liners or spacers.

The structure of the present invention can be manufactured in many ways with many different tools. Generally speaking, these methods and tools are used to form structures with dimensions in the millimeter and nanometer range. The methods and techniques used to fabricate the structures of the present invention use integrated circuit (IC) technology. For example, these structures are built on a wafer and patterned by photolithographic etching on the top of the wafer The material film to achieve. In particular, the manufacture of these structures uses three basic components: (i) depositing a thin film of material on a substrate, (ii) applying a patterning mask to the top of the thin film using photolithographic etching imaging, and ( iii) Etch the films according to the choice of the photomask.

Figure 1 shows the top electrode, switching material, and bottom electrode and other features and corresponding manufacturing procedures according to various aspects of the present invention. More specifically, the structure 10 of FIG. 1 includes a lower metallization feature 12 (eg, a conductive wiring structure) embedded in an insulator material 14. In a specific embodiment, the conductive wiring structure 12 may include a conductive wiring structure 12a for logic or peripheral devices and a conductive wiring structure 12b for a memory bit cell array. The conductive wiring structures 12a, 12b may be formed of any conventionally used metal or metal alloy material. For example, the conductive wiring structure 12a, 12b may be copper. For example, the insulator material 14 may be an oxide-based material. In a specific embodiment, the insulator material 14 may be, for example, SiO ₂ , TEOS, FTEOS, low-k or ultra-low-k SiCOH, or the like.

In a specific embodiment, the conductive wiring structures 12a, 12b are formed by traditional lithography, etching, and deposition methods known to those skilled in the art. For example, the resist formed on the insulator material 14 is exposed to energy (light) to form a pattern (opening). An etching process with selective chemistry (such as reactive ion etching (RIE)) will be used to form one or more trenches in the insulator material 14 through the openings in the resist. Then, the resist can be removed by a traditional oxygen ashing process or other known strippers. After the resist is removed, the conductive material can be deposited by any conventional deposition process, such as a chemical vapor deposition (CVD) process. Any residual material on the surface of the insulator material 14 can be removed by a conventional chemical mechanical polishing (CMP) process.

Still referring to FIG. 1, after the conductive wiring structure 12 is formed, an etch stop layer or diffusion barrier layer 16 may be deposited on the surface of the insulating material 14 above the conductive wiring structure 12. The etch stop layer or the diffusion barrier layer 16 can be, for example, a nitride, such as SiCN, SiN, AlN, or the like. An opening is formed in the etch stop layer or diffusion barrier layer 16 to expose the surface of the conductive wiring structure 12b.

The bottom electrode material 18, the switching material 20, the top electrode material 22, and the hard mask material 24 are sequentially deposited over the etch stop layer or diffusion barrier layer 16. In specific embodiments, the deposition of these materials can be performed by any conventional deposition process (including, for example, physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma enhanced CVD (PECVD) process, atomic layer Deposition (ALD), etc.). The bottom electrode material 18 is in direct electrical contact with the conductive wiring structure 12b.

The materials 18, 20, and 22 may be, for example, TiN, TaN, WN, Al, Ru, Ir, Pt, Ag, Au, Co, W, Cu, or a combination of multilayer conductive films. The hard mask material 24 on the top electrode 22 can be a carbon-based organic substance, such as CxHy, CxHyNz, oxide (e.g. SixOy, AlxOy, SiOxCy, high-k oxide), nitride (e.g. SixNy, SiOxNy, AlxNy, AlOxNy), Amorphous or polycrystalline silicon, or their multilayer stacked materials. In further specific embodiments, the hard mask material 24 may be a single film layer or a multi-layer film having oxides, nitrides, Si, and organics combined with any of the materials described herein. Materials 18, 20, 22, and 24 are made by traditional lithography and etching processes Patterning is performed to form vertical pillars 26 with vertically aligned sidewalls. The vertical pillar 26 is in direct contact with the conductive wiring structure 12b.

Still referring to FIG. 1, a dielectric material 28 is deposited on the vertical pillar 26 and the etch stop layer or diffusion barrier layer 16. The dielectric material 28 may be an oxide material, such as SiO2, TEOS, FTEOS, low-k or ultra-low SiCOH, etc., or any combination thereof. The dielectric material 28 can be deposited by a conventional CVD, PECVD, or ALD process followed by a planarization process. In a specific embodiment, the planarization process can be a CMP or an etch-back process. Alternatively, the dielectric material 28 may be applied by spin coating and curing/drying processes.

Figure 2 shows the post damascene lithography and etching patterning process for manufacturing trenches Mx+1 and vias Vx. More specifically, in FIG. 2, dual damascene or multiple single damascene processes can be used to form trenches Mx+1 and vias Vx. In a specific embodiment, before the hard mask material 24 is removed, the etch stop layer or the diffusion barrier layer 16 may be left or removed in the via hole Vx. In a specific embodiment, the etching process of the trench Mx+1 may be wider than the material stack (for example, the vertical pillar 26), thereby providing an improved margin for the self-aligned feature. The through hole Vx will expose the surface of the conductive wiring structure 12a.

Referring to FIG. 3, the hard mask material 24 is removed by a dry or wet etching process. The dry or wet etching process will be selective to the material of the hard mask material 24, so that no masking step is required. The removal of the hard mask material 24 will create a self-aligned via 30 that exposes the top electrode 22. In a specific embodiment, the etch stop layer or the diffusion barrier layer 16 may be removed during or after the removal of the hard mask material. In either case, the removal of the etch stop layer or diffusion barrier layer 16 will expose the surface of the conductive wiring structure 12a.

Fig. 4 shows the post-metallization structure and the corresponding manufacturing procedure according to various aspects of the present invention. In a specific embodiment, the conductive material 32 is deposited in the self-aligned via 30, the trench Mx+1, and the via Vx. The conductive material 32 in the self-aligned via 30 will be the interconnect 29 in direct electrical contact with the top electrode 22 and the upper metal Mx+1. No additional masking steps are required to complete this operation. The interconnect 29 will have vertical sidewalls aligned with the vertical pillar structure 26. Metallization can use metals (such as Cu, W, Al, Co, Ru, etc.) in combination with diffusion barrier materials (such as TiN, TaN, WN, etc.) for interconnection and Wiring structure. After metallization (eg, deposition of metal and barrier materials), a CMP process will be used to remove any excess material.

Figures 5 and 6 show an alternative structure with spacer materials and corresponding manufacturing procedures according to another aspect of the present invention. In the structure 10 a shown in FIG. 5, a spacer material 24 a is provided on the side wall of the hard mask material 24 on the vertical column 26. In a specific embodiment, the spacer material 24a may be deposited after the hard mask material 24 is deposited and patterned by conventional deposition, lithography, and etching processes. The spacer material 24a may be a nitride material (such as SixNy, SiCxNy, AlxNy, SiOxNy, AlOxNy, etc.) or an oxide material (such as SiOx, SiOxCy, TiOx, AlOx, etc.).

In FIG. 6, dual damascene or multiple single damascene processes are used to form trenches Mx+1 and vias Vx, as described in relation to FIG. 2. The hard mask material 24 is removed by a dry or wet etching process, as described with respect to FIG. 3. However, in this process, the spacer material 24a will not be removed, thereby defining the (surrounding) self-aligned via 30. In a specific embodiment, the conductive material 32 is deposited in the self-aligned via 30, the trench Mx+1, and the via Vx, as described in detail with respect to FIG. 4. In this specific embodiment, the interconnect 29 will have a stepped or narrower cross-section than the profile of the vertical column structure 26.

Figures 7 and 8 show an alternative structure with a liner material and corresponding manufacturing procedures according to another aspect of the present invention. In the structure 10b shown in FIG. 7, a liner material 24b is provided on the entire sidewall of the vertical column 26 (for example, on the materials 18, 20, 22, and 24). In a specific embodiment, the liner material 24b is deposited on the vertical pillar 26 to a thickness of about 1 nm to about 5 nm by a conventional deposition process (such as CVD). The liner material 24b may be a nitride material (such as SixNy, SiCxNy, AlxNy, SiOxNy, AlOxNy, etc.) or an oxide material (such as SiOx, SiOxCy, TiOx, AlOx, etc.). After depositing the liner material 24b, an anisotropic etching process is performed to remove the liner material 24b from the horizontal surface of the structure 10b (for example, over the hard mask material 24 and the etch stop layer or diffusion barrier layer 16).

In FIG. 8, the dielectric material 28 is deposited on the vertical pillars 26 (including the liner material 24b) and the etch stop layer or diffusion barrier layer 16, as described with respect to FIG. The trench Mx+1 and the via Vx are It is formed using dual damascene or multiple single damascene processes, as described in relation to FIG. 2. The hard mask material is removed by a dry or wet etching process, as described in relation to FIG. 3. However, in this process, the liner material 24b will not be removed, thereby defining the (surrounding) self-aligned via 30. In a specific embodiment, the conductive material 32 is deposited in the self-aligned via 30, the trench Mx+1, and the via Vx, as described in detail with respect to FIG. 4. The interconnect 29 will have vertical sidewalls aligned with the vertical pillar structure 26.

Fig. 9 shows an alternative structure 10c and the corresponding manufacturing procedure according to another aspect of the present invention. In a specific embodiment, the alternative structure 10c includes a double spacer defining a self-aligned through hole 30, that is, the spacer material 24a and the liner material 24b. As those skilled in the art should understand, the manufacturing process used to construct the structure 10c of FIG. 9 is a combination of the structures of FIGS. 5 to 8 and the corresponding manufacturing process, so no further explanation is needed here.

The method (etc.) described above is used in the manufacture of integrated circuit wafers. As a result, integrated circuit chips can be distributed by the manufacturer in the form of original wafers (that is, a single wafer with multiple unpackaged chips), as bare dies, or in packaged form. In the latter case, the chip is fixed in a single-chip package (such as a plastic carrier with wires attached to the motherboard or other higher-level carrier) or in a multi-chip package (such as one or both surfaces with surface interconnects or Ceramic carrier with embedded interconnection). Then in any case, the chip is integrated with other chips, discrete circuit components, and/or other signal processing devices into (a) intermediate products, such as motherboards, or (b) end products. The end product can be any product that includes integrated circuit chips, ranging from toys and other low-end applications to advanced computer products with displays, keyboards or other input devices, and central processing units.

The description of many specific embodiments of the present invention has been presented for illustration, but the present invention is not necessarily limited to the published form. Without departing from the scope and spirit of the specific embodiments described, those skilled in the art will understand many modifications and variations. The terminology used in this article is to best explain the principles of specific embodiments, practical applications or technical improvements of technologies found in the market, or to enable those skilled in the art to understand the specific embodiments disclosed herein.

12: Conductive wiring structure

12a: Conductive wiring structure

12b: Conductive wiring structure

14: Insulator material

16: Etch stop layer or diffusion barrier layer

18: bottom electrode material

20: Switch material

22: Top electrode material

26: vertical column

28: Dielectric materials

29: Interconnect

30: Self-aligned through hole

32: conductive material

Claims (20)

A semiconductor structure comprising: a lower metallization feature; an upper metallization feature; a bottom electrode directly contacting the lower metallization feature; one or more switching materials above the bottom electrode; a top electrode directly contacting The one or more switching materials; a via interconnection that contacts a top surface of the top electrode and a bottom surface of the upper metallization feature; and a spacer material that contacts a sidewall surrounding the via interconnection, And contact the top surface of the top electrode and the bottom surface of the upper metallization feature; wherein an outer sidewall surface of the spacer material is connected to each of the one or more switching materials, the top electrode and the bottom electrode One side wall is coplanar. The structure described in item 1 of the scope of the patent application further includes a peripheral device or logic device, which includes the lower metallization feature and the upper metallization feature connected together by an interconnect structure without any intermediate material . According to the structure described in claim 1, wherein the through-hole interconnection is a self-aligned through-hole interconnection, which is exposed and aligned with the top electrode. The structure described in item 3 of the scope of patent application, wherein the spacer material defines and surrounds the self-aligned through hole interconnection. The structure described in item 3 of the scope of patent application further includes a vertical alignment lining material Material, which defines that the self-aligned vias are interconnected and directly contact and surround the outer sidewall surface of the top electrode, the one or more switching materials, the bottom electrode and the spacer material, and the liner material by The spacer material is separated from the self-aligned via interconnection. The structure described in item 5 of the scope of patent application, wherein the spacer material is on an inner side of the vertical alignment liner material, which defines and surrounds the self-aligned via interconnection. The structure as described in item 1 of the scope of patent application, wherein the top electrode is formed of one or more of the following conductive materials: TiN, TaN, WN, Al, Ru, Ir, Pt, Ag, Au, Co, W, Cu or The combination of its multilayer film. According to the structure described in claim 1, wherein the bottom electrode, the one or more switching materials, the top electrode, and the spacer material surrounding the through hole interconnection have a plurality of vertical pillars forming a vertical column structure. The sidewalls are aligned, and the vertically aligned sidewalls further include a diffusion barrier layer contacting the bottom electrode. A semiconductor structure includes: a first metallization layer; a second metallization layer; and a vertical pillar connecting the first metallization layer to the second metallization layer, the vertical pillar including an alignment via A via interconnection and a spacer surrounding the aligned via interconnection, both the aligned via interconnection and the spacer contacting a top electrode of the vertical post and the second metallization layer; a peripheral device or A logic device comprising the first metallization layer and the second metallization layer, the first metallization layer and the second metallization layer by an interconnection without the alignment via interconnection and the vertical pillar Structures connected together; and a diffusion barrier material contacting the first metallization layer and the bottom electrode, An outer sidewall surface of the spacer and an edge of the top electrode have a plurality of coplanar sidewalls, and a lining material is on the coplanar sidewalls and contacts the coplanar sidewalls to form a vertical column structure. According to the structure of claim 9, wherein the alignment via is interconnected in a via, which exposes the top electrode and further includes contact with the spacer, a sidewall of the vertical column, and the diffusion barrier material A side wall structure. As the structure described in item 10 of the scope of patent application, the spacer defines the self-formed self-aligned via and completely surrounds and directly contacts the self-aligned via interconnection and a sidewall structure, and the sidewall structure contacts the The outer surface of one of the vertical columns. The structure described in item 11 of the scope of patent application, wherein the vertical column has a narrower cross section at the self-formed self-aligned through hole than the top electrode. The structure described in item 11 of the scope of the patent application, wherein the liner material defines the self-formed self-aligned through hole and surrounds the vertical column and the self-aligned through hole for interconnection. A semiconductor structure comprising: a lower metallization feature; an upper metallization feature; a bottom electrode directly in contact with the lower metallization feature; one or more switching materials above the bottom electrode; a top electrode Above one or more switching materials; a via interconnection that contacts the top electrode and the upper metallization feature; a spacer material that contacts a sidewall interconnection surrounding the via and contacts the top electrode A top surface and a bottom surface of the upper metallization feature; and a diffusion barrier material directly contacting the lower metallization feature and the bottom electrode; wherein the bottom electrode, the one or more switching materials, the top electrode and the bottom electrode The side walls of each of the outer surfaces of the spacer material are coplanar with each other and are coplanar with the through hole interconnection forming a vertical column structure. The structure according to claim 14, wherein the via interconnection is a self-aligned via interconnection, and the top electrode directly contacts the one or more switching materials. The structure described in item 14 of the scope of patent application further includes a peripheral device or logic device, which includes the lower metallization feature and the upper metallization feature connected together by an interconnect structure without any intermediate material . The structure described in item 1 of the scope of the patent application further includes a plurality of vertically aligned sidewalls, which interconnect all of one sidewall along the through hole. The structure described in item 1 of the scope of the patent application further includes a vertically aligned sidewall material that directly contacts and along the outer side of the bottom electrode, the one or more switching materials, the top electrode and the spacer material A wall surface is vertically aligned with all of the side wall, and the spacer material is between an inner surface of the side wall material and an outer surface of the through hole interconnection and contacts the inner surface of the side wall material and the through hole The outer surface of the interconnection. The structure described in item 1 of the scope of the patent application further includes a vertically aligned sidewall material that directly contacts with all of a vertically aligned sidewall along the bottom electrode, the one or more switching materials, and the top electrode And the outer sidewall surface of the spacer material, the through-hole interconnection is smaller than the vertical of the bottom electrode, the one or more switching materials and the top electrode in cross section The sidewalls are aligned directly, and the spacer material directly contacts the vertically aligned sidewall material and is located below the vertically aligned sidewall material, and the semiconductor structure further includes a diffusion that directly contacts the lower metallization feature and the spacer material Barrier material. The structure according to claim 9, wherein the vertical column includes a bottom electrode directly contacting the first metallization layer and one or more switching materials, and the one or more switching materials are above the bottom electrode Directly contact the top electrode.

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